Thanks to the recommendations of a number of reputable online fitness experts, a BBC documentary and an array of articles and studies; intermittent fasting has slowly but surely gained an increasingly reinforced reputation as the ultimate way to lose weight. It has been endorsed by many as the most efficient and healthy way to lose unwanted body fat whilst maintaining muscle mass. As a result the subject of intermittent fasting has generated a vast amount of interest and discussion on and offline.

It would be easy to dismiss intermittent fasting as the next fitness fad, but it is backed up by a substantial amount of research. Intermittent fasting is based upon the theory that our bodies evolved in the Paleolithic era (50,000 to 10,000 BC) to adapt specifically to a lifestyle and environment characterised by periods of famine and feast. The theory behind intermittent fasting dictates that these alternate periods of restricted caloric intake are required for optimal metabolic function.

Benefits of Intermittent Fasting
The list of proposed benefits relating to intermittent fasting are indeed extremely impressive. They include improved blood lipid profiles, increased growth hormone secretion, accelerated autophagy (the process of cells recycling waste matter), increased insulin sensitivity and studies on animals have also suggested it may have some beneficial effects relating to the prevention of cancer and cognitive function. One of the main mechanisms behind intermittent fasting and all these health benefits, appears to be a reduced secretion of a hormone called IGF-1. This is a hormone that accelerates the aging process and has been linked to a number of diseases, especially when present in the body in relatively high amounts.

Intermittent Fasting Benefits

Intermittent Fasting Protocols

Alternate Day Fasting
This protocol involves one day of consuming 1/5th of normally energy needs (between 400 and 700 calories depending on bodyweight), and on the next day consuming what you would normally eat – i.e. your usual daily diet. This alternate day fasting is normally continued for a period of up to 8 weeks, although some nutritionists, somewhat controversially, advocate doing it continuously.

The 5:2 Fast
Following this system, as you may have guessed by it’s title, involves spending 2 days a week on a diet that is extremely low in calories. Again 400 to 700 calories depending on body weight, is normally recommended on fasting days.
The fasting days should NOT be consecutive. Again this style of fasting is normally adhered to for up to 8 weeks at a time.

The 16:8 DietThis is where you normally stop eating at 8pm in the evening, and then don’t eat until 12pm the next day. You need to plan diligently for this protocol, ensuring you eat good quality food in your 8 hour window, and not rubbish to meet your calorie-needs.

Training and Intermittent Fasting
Studies have suggested that exercising whilst in a fasted state, although should be done under supervision and with care, can actually lead to improved athletic performance.

Keeping workouts short (less than 30 mins) and intense, can help enhance the use of fat as a substrate/fuel, whilst enhancing Growth Hormone secretion. Growth Hormone in turn, leads to an enhanced anabolic response – i.e. greater potential to build muscle.

Training in a fasted state can also enhance adaptation to endurance exercise. Studies have shown that training with extremely low levels of muscle glycogen/carbohydrate causes an increased “oxidative capacity” by enhancing the formation of new mitochondria (an element of muscle cells vital to endurance).

For bodybuilding purposes, an example fasting workout programme may look like this:

BCAAs
Many fitness professionals advise people to take 10g of BCAA approximately 20 minutes before and 10g immediately after training in a fasted state. The theory behind this is that, whilst the body is still starved of carbohydrate, it will experience the same increased secretion of Growth Hormone, and the BCAA supplementation will capitalise on this, further increasing protein synthesis. Interestingly, fitness professionals appear to disagree on whether or not the calories in BCAA should be counted towards your daily total. 10g of BCAA contains around 40 calories.

Whey Protein
Whey protein isolate or concentrate can be taken after a workout but the additional calories need to be accounted for when fasting. 1 scoop of whey protein powder will contain around 100 calories – check the label to find out exactly.

Fish Oil
Other supplements may be required to make meals during fasting days, “nutrient dense” – you should make those 500 or so calories as nutritious as possible. Supplements that could help you achieve this, include fish oil liquid or capsules, and ‘green powders’ such as wheatgrass and spirulina can also be consumed and are recommended by many nutritionists.

Intermittent Fasting Results
A quick Google search of the phrase “intermittent fasting results” returns a huge number of before and after pictures that apparently substantiate the claims of fat loss achieved with intermittent fasting.
Personally however, I believe it is best to look for information from trusted, authoritative sources and scholarly studies. The article on the BBC website for example, states that Dr Michael Mosley, lost a stone in 5 weeks, and his cholesterol profiles improved, as did his markers of type II Diabetes. His IGF-1 levels also dropped. In addition, there are a number of studies showing that intermittent fasting is equally as effective as continuous energy restriction for achieving weight loss and improving health.

Final Thoughts
Despite the mounting research and increasing amount of anecdotal evidence; clinical nutritionists and dieticians generally do not recommend intermittent fasting for weight loss or health benefits. They instead recommend eating at least 2000 calories per day for men and 1500 a day for women, and suggest that fasting should only be done under supervision.

Keep this advice in mind if you do attempt an intermittent fasting diet. Remember that there are possible side effects that may include dizziness and sleepiness; something that could obviously be quite dangerous. I would also advise to keep properly hydrated by drinking plenty of water and try a few days with a more moderately reduced caloric intake before attempting a full fast.